program09.c

#include <stdio.h>
#include <stdlib.h>
#define MAX_FRAMES 10
#define MAX_PAGES 50
int pages[MAX_PAGES];
int pageFrames[MAX_FRAMES];
int total_pages, frames;
// Prototypes
void FIFO();
void LRU();
void OPTIMAL();
int findPage(int page, int pageFrames[], int frames)
{
    for (int i = 0; i < frames; i++)
    {
        if (pageFrames[i] == page)
        {
            return i;
        }
    }
    return -1;
}
void initialize()
{
    for (int i = 0; i < frames; i++)
    {
        pageFrames[i] = -1; // initialize page frames to -1 indicating they're empty  }
    }
    void printPageFrames()
    {
        for (int i = 0; i < frames; i++)
        {
            if (pageFrames[i] != -1)
            {
                printf("%d ", pageFrames[i]);
            }
            else
            {
                printf("-- ");
            }
        }
        printf("\n");
    }
    void FIFO()
    {
        int next_replace = 0;
        int page_faults = 0;

        initialize();

        for (int i = 0; i < total_pages; i++)
        {
            if (findPage(pages[i], pageFrames, frames) == -1)
            {
                pageFrames[next_replace] = pages[i];
                next_replace = (next_replace + 1) % frames;
                page_faults++;
                printPageFrames();
            }
        }
        printf("FIFO - Total Page Faults: %d\n", page_faults);
    }
    void LRU()
    {
        int page_faults = 0;
        int used[MAX_FRAMES] = {0}; // Used to keep track of usage
        initialize();

        for (int i = 0; i < total_pages; i++)
        {
            int found = findPage(pages[i], pageFrames, frames);
            if (found == -1)
            { // Page fault
                int lru = 0;
                for (int j = 1; j < frames; j++)
                {
                    if (used[j] < used[lru])
                    {
                        lru = j;
                    }
                }
                pageFrames[lru] = pages[i];
                page_faults++;
                printPageFrames();
            }
            for (int k = 0; k < frames; k++)
            {
                used[k]++;       // Increment the use time of all frames  }
                used[found] = 0; // Reset the frame that was just referenced  }
                printf("LRU - Total Page Faults: %d\n", page_faults);
            }
            void OPTIMAL()
            {
                int page_faults = 0;

                initialize();

                for (int i = 0; i < total_pages; i++)
                {
                    if (findPage(pages[i], pageFrames, frames) == -1)
                    { // Page fault  int opt_index = -1, farthest = i;
                        for (int j = 0; j < frames; j++)
                        {
                            int k;
                            for (k = i + 1; k < total_pages; k++)
                            {
                                if (pageFrames[j] == pages[k])
                                {
                                    if (k > farthest)
                                    {
                                        farthest = k;
                                        opt_index = j;
                                    }
                                    break;
                                }
                            }
                            if (k == total_pages)
                            { // Not found in the future  opt_index = j;
                                break;
                            }
                        }
                        if (opt_index == -1)
                            opt_index = 0; // If all are equally likely  pageFrames[opt_index] = pages[i];
                        page_faults++;
                        printPageFrames();
                    }
                }
                printf("Optimal - Total Page Faults: %d\n", page_faults);
            }
            int main()
            {
                printf("Enter number of frames: ");
                scanf("%d", &frames);
                printf("Enter number of pages: ");
                scanf("%d", &total_pages);
                printf("Enter page reference string:\n");
                for (int i = 0; i < total_pages; i++)
                {
                    scanf("%d", &pages[i]);
                }
                FIFO();
                LRU();
                OPTIMAL();
                return 0;
            }